Concrete Sulfate Attack Flashcards
(7 cards)
1
Q
Primary
A
C3A + Gypsum + H20 = Ettringite
but if not enough gypsum then
C3A + Ettringite = calcium monosulfonate
2
Q
Secondary
A
MSA + sulfate ions + H20= Ettringite
this expands concrete interanlly cracking
3
Q
Why is type 5 cement high sulfate resistant
A
has the least amount of C3A
4
Q
what do pozzolans do to concrete permeability
A
reudce permeabilty, making it harder for sulfate ions to attack concrete
5
Q
External
A
ACI 318 Exposure Categories and classes for sulfate in soil and water
ACI 201 Requirements to protect against sulfate attack from external sources
6
Q
Internal
A
DEF: delayed etteringite formation
- common in mass concrete
-temperature above 158, delayed ettringgirte and when it falls below 158 it becomes a solid and cracks
- takes years to detect
7
Q
A
